Why does rebooting lose all settings?

If you need to do a factory reset please do so by clicking the button in "Settings > Miscellaneous".

The button on the back of the NETDUMA router is the “factory reset” button, and should only be used in exceptional circumstances when you cannot access the interface. Should you have accidentally pressed this button, you can access your saved settings if you exported your profile beforehand. If you did not export your profile, then your settings will have been lost.